Let me take a stab at this one
When the engine rocks under load (like when you mash the gas to the floor) you're loosing that torque because it's absorbed in the rubber engine/transmission mounts. That creates a lag between the time you smash the gas, and the car reacts...not much, but about a second from what I can remember on my car.
The engine damper works like a standard shock absorber, but a VERY stiff one. It bolts to the engine, and then to the firewall and it keeps the engine in it's place, and doesn't allow it to rock in its mounts.
What you gain, is much improved throttle response which means quicker acceleration (especially from a stop or coming out of a turn under throttle.) It should also improve the life of the rubber engine mounts, and transmission mounts because the movement is limited. That hasn't been confirmed yet because these damper kits are fairly new and I don't think anybody has driven the 30K miles or so that it usually takes to break a rear tranny mount.
Let me know if you have anymore questions. I'm kinda like an expert on them now!
